
Class 



SyF_2^ 



Book__^K-li 



UNITED STATES DEPARTMENT OF AGRICULTURE 




jry-^'^>-r<. 



BULLETIN No. 849 

Contribution from the Bureau of Animal Industry 
JOHN R. MOHLER, Chief 




Washington, D. C. 



July 16, 1920 



CITY MILK PLANTS: CONSTRUCTION AND 
ARRANGEMENT. 

By Ernest Kelly and Clakence B. Clement, Dairy Division. 



CONTENTS. 



Page. 
Statement of present conditions — 1 
Pi-imary considerations in establish- 
ing a plant 2 

Hints to prospective builders 3 

Location of plant 4 

Classes and types of plants 6 

Construction of plant 9 

Size of building and number of 

stories 9 

Type of building 9 

Materials of construction 10 

The cold-storage room 12 

Arrangement of plant 12 

Handling the milk at entrance- 12 



Page. 
Arrangement of plant — Continued. 
Milk pumps compared with ele- 
vators 14 

Loading delivery wagons IG 

Unloading delivery wagons 19 

Division of rooms 19 

Size of rooms 21 

Arrangement of rooms 24 

Arrangement of equipment and 

machinery 25 

Effect of arrangement of plant 

on labor requirements 27 

Sanitary requirements 30 

Cost of plant 33 

Conclusions 34 



STATEMENT OF PRESENT CONDITIONS. 

The market-milk industry has assumed enormous size and im- 
portance. By market milk is meant milk consumed in the fluid state, 
as distinguished from milk used for butter, cheese, condensed milk, 
and other products. It is estimated that in 1917 more than 16 billion 
quarts of market milk were consumed in the United States, which at 
10 cents a quart would have been worth more than If billion dollars. 
Of course much of this milk was used on farms and in small towns, 
but probably not less than one-third was used in the larger cities. 
The greater part of the city milk was handled by so-called " middle- 
men " in city milk plants. These milk plants represented an invest- 
ment of about 100 million dollars in buildings and machinery. The 
cost of land and delivery equipment would bring the total to con- 
siderably more. 

Such an important business entails a great responsibility. In- 
fants, children, and invalids, as well as healthy adults, depend to 



15880J 



-20— Bull. 849- 



V 



"^ 



^ 



2 BULLETIN 849, U. S. DEPARTMENT OF AGRICULTURE. ^ \A^ 

a great extent upon market milk. The supply must be brought some- 
times from a distance of 300 or 400 miles, pasteurized, bottled, and 
delivered to the consumer generally each morning before breakfast. 
Furthermore, the milk must be handled under rigid sanitary condi- 
tions. For this business the modern city milk plant has been devel- 
oped. These plants are constantly being remodeled, and new ones 
are being built to meet the latest advances in sanitation. 

The purpose of this bulletin is to furnish specific information on 
the construction and arrangement of modern milk plants as an aid 
to those who wish to build new plants or remodel old ones. The 
information presented is based upon data obtained from surveys made 
of many of the principal plants in the larger cities of the United 
States. 

PRIMARY CONSIDERATIONS IN ESTABLISHING A PLANT. 

While starting a milk plant which insures a safe and adequate 
milk supj)ly for a community is a laudable enterprise, it must be 
remembered that such ventures are not always successful. Many 
milk plants have failed, not because of faulty management or 
changed conditions, but because the milk plant should not have been 
established in the first place. Before the prospective operator 
engages in the milk business the following questions should be 
answered to his satisfaction. 

1. Is the person who is to manage the plant familiar with the milk 
business ? Unless a capable manager can be obtained the chances of 
success will be greatly lessened, as the success of a milk business 
depends primarily upon the manager. Besides being a good business 
man, the manager must be acquainted with the details of handling 
milk and of milk-plant operation. A man may have the proper 
character, personality, and business ability to manage some other 
kind of business and yet make a failure of the management of a milk 
plant, because he lacks the technical knowledge required. 

2. Is there capital enough available to equip and operate a modern 
sanitary plant until it reaches a paying basis ? 

3. Is there a suflScient supply of milk of proper quality available 
or can enough be made available to operate the plant successfully? 

4. Is there a steady demand for milk in the locality under con- 
sideration and is this demand being met by dealers already in the 
business? 

5. "V\niat type of competition will be met with? 

C). Wliat is the attitude of the local health department ? A capable 
health department can be of great helj:* to a plant that is putting out 
a high-grade product. 

7. Wliat is the local labor situation? 



CITY MILK plants: CONSTRUCTION AND ARRANGEMENT. d 

8. Can the householders in the community be taught the value of 
milk as a food and be led to increase their demand ? Are they able 
to j)ay a fair price for a high-grade product, and will they pay their 
bills promptly? 

There are also minor considerations, but if the foregoing condi- 
tions are favorable tlie advisability of establishing a new plant in 
the vicinity will be greatly enhanced. 

HINTS TO PROSPECTIVE BUILDERS. 

The construction of a city milk plant requires careful study and 
planning. The building represents a large investment, as is shown 
in Table 8 under " Investment in milk plant." It is important, there- 
fore, that the plans be carefully laid. The efficiency of the plant 
depends to a large degree upon the type of equipment used and the 
arrangement of the various rooms and machinery. It is possible 
for a well-arranged plant to effect great economies in labor, while 
a poorly planned plant may become a continual source of expense 
because of the extra labor required. 

Any one contemplating building a new plant will do well to visit 
various up-to-date plants in different cities to get the latest ideas 
on construction, layout of rooms, and equipment. If it is impossible 
to visit other plants, plans and specifications sometimes can be 
obtained and ideas gained from them. By combining other dealers' 
ideas with his own the prospective builder can usually incorporate 
the best features of all in the new plant. 

After selecting a site for the plant and determining about what is 
needed, the ^prospective builder should explain his general plan to a 
competent architect, who will draw up tentative sketches and plans 
which may then be studied in detail. Of course the type of machin- 
ery to be used must have been previously decided upon, since the gen- 
eral arrangement of the plant will depend a great deal on the type 
used. 

It may be well to have several plans drawn, each adapted to a par- 
ticular type of machinery. In case changes are found necessary they 
should be made in the plans before beginning the construction, as it 
is expensive to make alterations. It Avould be well also to have the 
plans reviewed by others experienced in the business and by health 
officials before the final plans are drawn. 

After the plans and specifications of the building have been decided 
upon, bids should be obtained from several contractors in order to 
get the work done as reasonably as possible. 

For a plant of small capacity much less detail is necessary and the 
plans can be completed frequently without the aid of an architect. 



BULLETIN" 849, IT. S. DEPARTMENT OF AGRICULTURE. 
LOCATION OF PLANT. 

The principal points to bear in mind in locating a milk plant are 

1. Ease of access from as many sides as possible. 

2. Value of property. 

3. Cost of getting the milk to the plant. 

4. Proximity to distribution center. 

5. Advertising possibilities. 

6. Opportunity for retail counter cash trade. 

7. Nearness to city water supply and electric power. 

8. Avoidance of heavy traffic surroundings. 

9. Good drainage. 

10. Pure air and clean surroundings. 




l"ni. 1. — Exteriur ul' a uhkIi'I'u city milk plant. 

Ease of access to the j)lant is very important. It is difficult to ar- 
range a plant economically and conveniently unless it can be ap- 
proached from at least two sides. A plant on a corner lot with an 
alley in the rear is desirable, but is seldom obtained in the down-town 
section of a city without great expense. 

The high valuation of down-town property in many cities would 
be prohibitive for the location of a milk plant. In small cities, how- 
ever, the extra advertising value and the cash trade gained by having 
the plant in the down-town section would often warrant such a loca- 
tion. 

The cost of getting milk to the plant is an important consideration. 
If the bulk of the milk is received by railroad it may be advantageous 
to locate the plant near the railroad station, but if the milk is handled 



cfiTY MILK plants: construction and arrangement. 5 

largely by truck, the vicinity where most of the milk comes into the 
city would be a convenient location. In case a large proportion of 
the milk is to be handled as bulk goods or wholesale deliveries, the 
wholesale section would have the advantage. If branch plants are to 
be established it may be well to locate the main plant where it can 
most easily receive the milk from the railroads. It is much less ex- 
jiensive to transfer bulk goods by truck than bottled goods, so that 
many dealers find it advantageous to have a main plant where most 
of the milk is received and to have branch plants near centers of dis- 
tribution. Usually most of the trade of the branch plants is retail, 
while the down-town plant handles the greater portion of the: whole- 
sale trade. One plant having two branch j)lants had routes as fol- 
lows : 



• 


Wholesale 
routes. 


Retail 
routes. 




12 
4 
3 


39 

26 
28 


Branch No. 1 


Branch No. 2 





By locating the plant near the center of distribution, delivery 
costs may be considerably lessened and in some cases two delivery 
trips may be made during the day. 

Some dealers plan to establish the main plant in or near the section 
of the city where considerable development is anticipated. In this 
way they endeavor to obtain the trade of people moving into that 
section and the plant itself acts as an advertisement. 

To serve as an advertising medium the plant must be situated 
where there is considerable travel, as in a retail shopping district, or 
. at a street-car transfer point. The value of this form of advertising 
depends ujDon local conditions. In a small city it may be of consider- 
able importance. The retail counter cash trade is usually of small 
importance in a large city, but in a small or medium-sized town this 
trade is often well worth considering. A plant on a much-traveled 
highway should draw this trade. 

In few cities is there difficulty in getting an adequate supply of 
water and electricity, but, nevertheless, it is well to consider these 
items. Congestion of traffic is of small consequence in a small town, 
but in a large city it may assume considerable importance. 

Good drainage for the plant and clean surroundings are essential 
for an up-to-date plant. Some plants are opposite parks and the air 
is very free from dust, while at plants in a thickly settled part of 
the city it is often necessary to filter the air that comes into the 
building. 

In general, there are three locations in cities that may be selected 
for a milk plant: (1) In the wholesale district near the railroad, 



6 BULLETIN 849, tJ. S. DEPARTMENT OF AGRICULTURE. 

(2) in the down-town retail section of the city, and (3) in the resi- 
dential section. Heretofore it has been the general custom to locate 
the plant in the wholesale district near good railroad facilities. The 
tendency in recent years, however, has been to build it near the center 
of distribution rather than near the railroad teniiinal. 

The advantages of having a milk plant in the wholesale district 
are: 

Hailroad facilities make it more convenient for receiving the 

milk. 
It is a considerable distance from the residence districts, and 

there are less likely to be complaints of noise, smoke, etc. 

The disadvantages of locating a plant in the wholesale district are : 

It is away from the center of distribution. 

There are no advertising benefits. 

The district usually is rather insanitary and the air is filled 

with dust. 
Property is often expensive. 
Few retail counter sales are made at the plant. 

The chief advantages of being in the retail district are : 

Advertising benefits. 

Retail counter sales, which are valuable not only for the actual 
sales made but for the new trade obtained thereby. 

The principal disadvantages in the retail district are : 

Property is expensive. 
Less convenient for receiving milk. 
May not be convenient for distribution. 
More street traffic. 

The advantages of a plant in the residential district are : 

It is nearer the center of distribution and property is less 

expensive. 
Retail counter sales are made and new customers obtained at 

the plant. 
Pure air. 
Less congestion of traffic and more quiet surroundings. 

The disadvantages in the residential district are : 

Poor railroad facilities. 
Less advertising benefit. 
Possible restrictions in regard to operation. 

CLASSES AND TYPES OF PLANTS. 

Plants may be classified, according to the method of handling the 
milk in the plant, into the following G classes : 

1. Gravity, more than one stoivj. — In this class of plants the milk 
in cans is elevated above the first floor and dumped. It then flows 
by gravity through pasteurizing and other machinery without the 
use of a milk pump. 



CITY MILK plants: CONSTRUCTION AND ARRANGEMENT. 7 

2. Gravity and pump, more than one story. — Milk is elevated in 
cans above the first floor and dumped. It flows by gravity through 




Fig. 2. — General view of equipment in gravity plant, class 1. 

part of the machinery, but pumps are used also before it reaches the 
filler. 

Classes 1 and 2 are rather uncommon, as most dealers seem to con- 
sider it uneconomical to elevate the milk in cans above the first floor. 



8 BULLETIN 849^ U. S. DEPAETMENT OF AGRICULTURE. 

From the ideal sanitary standpoint class 4 is to be preferred. Most 
dealers, however, do not consider it objectionable to pump the milk 
before pasteurization, provided the pump is of the right type and 
properly taken care of. The economy of dumping milk and leaving 
the cans on the ground floor is of considerable importance and much 
labor, time, and power may be saved by handling cans in that way 
rather than by elevating the full cans and, after dumping, sending 
them back on an elevator. Wliere there is not room enough on the 
ground floor for weighing, sampling, and grading it may be con- 
venient to send the milk upstairs in cans. This system as a rule is 
more expensive, as is shown later in Table 2. 

3. Pump to higher level^ then gravity. — The milk is dumped into 
a tank on the first floor and pumped to a floor above, whence it flows 
through the various pieces of apparatus by gravity, without the fur- 
ther use of a milk pump. 

Some of the most modem large plants, which vary in height from 
2 or 3 stories upward, come under class 3. It is less objectionable to 
pump milk before pasteurization, when contamination can do less 
harm, than after. This type of plant also has the desirable feature 
of dumping and weighing the milk on the ground floor and is more 
economical in receiving milk than plants in classes 1 and 2. 

4. Pump to higher level^ then gravity and pump. — The milk is 
pumped from the first to a floor above. From that point it is handled 
by pumps, or partly by pumps and partly by gravity. 

Many of the larger plants belong to class 4. This type has the 
economical advantages of the plants of class 3 and in addition per- 
mits greater economies in labor by the fact that the various pieces of 
apparatus are comparatively close together, and in some cases on 
fewer floors. In most of the plants of class 4 milk is pumped after 
pasteurization and the number of milk pumps and length of milk 
piping required are usually greater than in plants of the other classes. 
Many of the plants studied in this class were comparatively old. 

5. Gravity., one story. — The milk is handled on one floor without 
milk pumps. Large quantities of milk can not be handled rapidly 
in such plants, and only the smaller plants come under this head. 
The plants of this class include a few small ones where the pasteur- 
izer was raised on a platform and the milk dumped directly into it. 
Those handling between 501 and 1,000 gallons daily were raw-milk 
plants. 

G. Pump, one story. — The milk is handled on one floor, one or more 
pumps being used. Class 6 includes some of the less up-to-date 
plants, which are usually frame buildings, built some time ago. The 
amount of milk piping required is comparatively large. Many of 
the smaller plants come under class 6 ; 48 out of a total of 55 handling 
less than 500 gallons each dailv were in this class. A few of the 



CITY MILK plants: CONSTRUCTION AND ARRANGEMENT. 



9 



larger j^lants were included, but in most cases they were old and 
poorly arranged. In one of the latter as much as 300 feet of milk 
piping was used. Considerable economy of labor is often possible 
in i^lants of this type, however, as the one-floor system usually re- 
quires fewer men. 

It is evident that plants in class 2 have few advantages over those 
in classes 3 and 4. They have the disadvantages mentioned in re- 
gard to time and labor of getting the milk upstairs, and pumps are 
used after pasteurization, which is not the case in classes 1 and 3, 
in which milk flows by gravity from the pasteurizer through the re- 
mainder of the equipment. One advantage the}^ may have over the 
j)lants of class 3 is that less milk piping is required, for there is no 
piping from the ground floor to the receiving room upstairs. 

A total of 174 plants of the principal dealers in the larger cities 
of the United States falls into the following classes: 



Class. 


Plants. 


Clasc. 


riants. 


1 


2 
5 

17 


5 


10 


2 





83 


3. 


Total .... 




4 


174 









Of the 83 plants in class 6, 48 each handled daily 50 gallons or 
less, and of the 57 plants in class 4, 29 handled 3,000 gallons or more 

CONSTRUCTION OF PLANT. 

SIZE OF BUILDING AND NUMBER OF STORIES. 

In planning a milk plant, provision should be made for a building 
large enough to accommodate a reasonable expansion of the business. 
If possible the building should be so laid out that by the addition 
of more units of machinery the capacity of the plant can be increased 
from time to time without interfering with the convenient arrange- 
ment of the apparatus. Sometimes provision is made for adding 
another story. 

A study of 105 representative milk plants showed that most of 
those handling less than 1 ,000 gallons daily have 1 story, while those 
handling from 1,000 to 5,000 gallons have 2 stories. Plants handling 
more than 5,000 gallons varied from 2 to 5 stories. 

TYPE OF BUILDING. 

The type of building selected depends upon local conditions and 
the type of machinery to be used. The more recentlj'^ built plants 
are usually from 2 to 3 stories. There are but few advantages in a 
higher building, as labor requirements increase with the height. 
A gravity system for handling milk can be arranged as well in a 
158803°— 20— Bull. 849- 2 



10 BULLETIN 849, V. S. DEPARTMENT OF AGRICULTURE. 

plant of 2^ stories as in a higher one. By either elevating or pump- 
ing the milk to a tank 2 or 2| stories high, gravity will do the work ; 
that is, the milk will flow through the clarifier and the pasteurizer 
into the bottk-filling machinery without the use of a pump. 

The principal advantage of building a higher plant is the smaller 
ground area needed when the plant is in a thickly settled part of the 
city; however, the tendency to build farther awav from the down- 
town section is increasing, so that this consideration becomes of 
minor importance. The appearance of the building from the street 
is important, as it serves as an advertisement. 

While the size of the plant as well as the number of stories de- 
pends on the quantity of milk to be handled, it should be so planned 
that one man can remain on one floor and not have to go from one 
floor to another in doing his work. Much time may be wasted if the 
men have to go upstairs and downstairs in their daily duties. 

The ceiling of the plant should be at least 12 feet high. A^Tien 
the pasteurizing equipment is on the balcony, midway between the 
ground floor and the second floor, the handling room and the bot- 
tling room should be two full stories. 

MATERIALS OF CONSTRUCTION. 

The materials used for the construction of the plant depend a 
great deal on local conditions. The most satisfactory materials that 
may be used are reinforced concrete, hollow tile with cement finish, 
or selected brick. Cement blocks are also used to a limited extent. 
When concrete is used, the inside walls should be finished with a 
smooth surface and protected with paint that will stand hot water 
and steam. 

At present the proportion of brick plants and wooden plants is 
large, but concrete is becoming very popular in many localities and 
is probably the most suitable for a milk plant. It is practicallj^ fire- 
proof, very sanitary, weather resistant, and durable. Hollow tile 
with stucco finish is also much used for milk plants. With that 
type of construction the inside walls must be finished with cement 
or similar material. In certain localities cement blocks are used. 
This form of construction is usually found in the smaller plants 
and is very satisfactory, provided the material is not too expensive. 
The wood-frame buildings in nearly all cases are old ones. Many 
plants are now built of selected brick with cement finish on the 
inside, which is a very satisfactory type of construction. 

INSIDE WALLS ANU CEILINGS. 

For the inside walls select a material that will provide a smooth, 
easily cleaned surface that is durable and waterproof. Concrete or 
cement is very commonly used and is quite satisfactory. This ma- 



CITY MILK plants: CONSTRUCTION AND ARRANGEMENT. 11 

terial can be finished with a smooth surface which is sanitary and 
can be easily washed with the hose. Walls should be coated with a 
paint as nearly waterxDroof and steamproof as possible. When 
wooden walls or partitions are used, the concrete of the floor should 
extend about 2 feet up the wall, as that part of the wall is exposed 
to water a large part of the time. 

For inside walls of rooms where milk is handled, enamel brick, 
tile, enamel cement, or cement plaster is satisfactory. Tile or enamel 
brick is preferable but rather expensive. The different materials 
used in 20 plants which had special material for these rooms were as 
follows: Enamel brick, 12 plants; tile, 1 plants; cement plaster, 1 
plant ; enamel cement, 3 plants. 

All the foregoing materials have a smooth surface and are easily 
kept clean. They give the room a sanitary appearance and are good 
reflectors of light. Ejiamel brick is less expensive than tile and is 
much used for the walls of milk-handling rooms. 

Ceilings are usually constructed of materials similar to those used 
on the inside walls. The following were found in various plants: 
Wood, concrete, cement plaster, plaster on lath, and galvanized 
metal. As in the case of the inside walls, the ceiling should be 
smooth, durable, easily cleaned, and as nearly waterproof and steam- 
proof as possible. 

FLOORS. 

Several large plants had wooden floors, but wood is a very poor 
material for floors where milk is handled. Wood is not durable and 
the milk soaks into it, causing bad odors and insanitary conditions. 
If a wooden floor is very tight it may be satisfactory for a short time 
if it is cleaned often, but its period of usefulness is short. Some 
form of concrete with a waterproof finish is the most desirable ma- 
terial. Frequentl}- a hardener of steel filings mixed with the cement 
is used to form the finish, which makes the floor wear better. Some- 
times, where an old building is used for a milk plant, a concrete floor 
ma3^ be laid over wood, if the underpinning is strong enough. If 
properl}' laid, a concrete floor is smooth and can be easily cleaned 
with hot water from a hose. Milk does not soak into concrete floors 
as it does into those of brick or wood. Concrete floors should have 
a good foundation with at least 3^ inches of concrete below the top 
surface. Asphalt is sometimes used, but it is not very satisfactory 
because heat tends to soften it. 

A tile floor in the bottle-filling room is desirable. Although more 
expensive when properly laid, it makes a good appearance, is durable, 
easily cleaned, and very sanitary. 

Iron plates embedded in the cement protect the floor in rooms 
where cans and trucks are constantly being handled. An unpro- 
tected concrete floor wears out quickly if cans are continually rolled 
over it. 



12 BULLETIN 849, U. S. DEPARTMENT OF AGRICULTURE. 

Floors in the milk-handling or washing rooms should have a slope 
of about one-fourth inch per foot toward the floor drains. Drains 
should be located when the floor is laid to insure a correct slope of 
floor and should be trapped and connected with the sewer. They 
should be from 6 to 8 inches wide and have perforated, removable 
covers. Great care should be taken in laying the floor to avoid 
making hollows in which water may collect. Before installing the 
plumbing it is advisable to be sure that it conforms to local plumbing 
regulations. 

THE COLD-STORAGE ROOM. 

The milk-storage or refrigerator room must be well insulated to 
keep the milk always at low temperature. The most common insulat- 
ing materials are cork board, mineral wool, vegetable fiber, sawdust, 
and shavings, wliich are used as fillers in walls of wood, cement, or 
masonry. Cement should be put over the insulating material for the 
inside walls and ceilings to protect that material from moisture. The 
floors of the refrigerator should be of concrete laid solidly on the 
insulating material. The most satisfactory construction is about 4 
inches of cork-board insulation with cement on the inside and out- 
side.^ Good drainage to a drain pipe, carefully trapped to prevent 
warm air from entering the room, is very important. 

ARRANGEMENT OF PLANT. 

HANDLING THE MILK AT ENTRANCE. 

In the arrangement of rooms and machinery, economy of operation 
as well as sanitation must be considered. In the layout of the plant, 
provision should be made for the convenient and rapid loading and 
unloading of wagons. This applies to the delivery wagons and also 
to the trucks which bring the milk to the plant. 

Some plants are so arranged that it is necessar}^ for the trucks to 
be unloaded inside the building. Such a system is not conducive to 
rapid unloading. When the trucks drive inside the building there is 
a smaller space to turn in, and greater danger of contamination from 
dirt and dust of the street coming in through the open door of the 
receiving room. The use of a platform on the outside of the plant 
at the receiving room allows the milk to be handled much more 
readily. The platform need be only a few feet wide, but there should 
be ample space for two or more trucks to drive up to the platform 
at one time. 

Upon the arrival of the trucks the milk is unloaded at once and 
sent to the receiving room, where it is dumped immediately. There 
is no needless driving and backing, as is the case when the trucks 
unload in the interior of the plant. If the unloading platform is 

' For detailed information as to construction of storage rooms, see U. S. Department 
of Agriculture Bulletin 98. 



CITY MILK plants: CONSTRUCTIOlSr AND ARRANGEMENT. 



13 



outside, the truck can be quickly unloaded and another driven up 
immediately and unloaded. Usually two or more trucks can be un- 
loaded at one time, which is not the case if they are unloaded within 
the plant. 

Some plants with platforms outside greatly expedite the unloading 
and dumping of the milk by the use of roller conveyers. The plat- 
form should be covered to protect the workmen from the weather. 
The cans as they are removed from the truck are placed on the con- 
veyers, on which they are carried to the dump or weigh tank. The 
cans may then be rolled on more conveyers to the can washer and 
thence to the can racks or back to the trucks. If the milk is received 
in this way the receiving room can be kept cleaner and the work can 
be done much more economically than if the trucks are driven into 
the building. 

The unloading platform should be as close as possible to the re- 
ceiving room and should be level with the floor of the truck, so that 
the cans of milk may be readily rolled from the truck. By having 
the dump tank close to the receiving platform and also lowered to 
the level of the floor, milk may be handled rapidly and with few 
men. It is desirable, however, to have the receiving room well in- 
closed and far enough from the street to reduce to a minimum the 
chances of contamination of the milk from that source. At many 
plants the platform can be most advantageously placed at some dis- 
tance from the receiving room, even though more time and men may 
be required to receive and dump the milk. At such plants, much time 
and labor can usually be saved by the use of conveyers. 

The plant should be so arranged that there will be no confusion of 
the milk trucks with the delivery wagons. A convenient arrangement 
is to have the receiving platform on one side of the building and the 
loading platform for delivery wagons on the other side. 

In Table 1 a comparison is made of a few plants to illustrate three 
methods of arrangement for receiving the milk. 

Table 1. — Economy of various arrangements of plants for receiving and 

(lumping millc. 



Type of plant. 


Number 

of 
plants. 


Average 
number 
of cans 
received 

per 
plant. 


Average 
number 
of men 

per 
plant. 


Average 

time 

per 

plant. 


Average 

hours of 

labor per 

plant. 1 


Average 
hours of 

labor 
per 100 

cans. 


Average 
time 

per 100 
cans. 


Average 

cans 
handled 
per hour. 


Truck unloaded inside plant 
and milk either dumped at 
ground floor or sent up- 
stairs on elevators (no plat- 
forms used) 

Trucks unloaded at platform 
and milk sent to receiving 
room on conveyers 


3 
3 


207 
G43 
500 


3.3 

4 

2.5 


Hours. 
2.5 

4 

3.2 


.S.3 
19.0 

8.7 


4.0 
2.9 
1.7 


Hours. 
1.2 

.8 

.05 


82.6 
l''l 


Trucks unloaded at platform 
and milk dumped in tank 
near by 


154 







1 "Man hours. 



14 



BULLETIN 849, U. S. DEPARTMENT OF AGRICULTURE. 



When the trucks were unloaded inside of a building that has no 
platform, considerably more time and labor were required to handle 
100 cans of milk. The system of using conveyers to send the milk 
from the platform to the receiving room required more men and 
time than when the milk was dumped direct without the use of con- 
veyers. This is due to the fact that at the plants where no conveyers 
were used the dumping tank was quite close to the receiving platform 
and less handling was required. The dump tanks at these plants 
were also sunk in the floor, so that very little lifting of the cans was 
required. In the plants where the conveyers were used the receiving 
room was uuich better protected from contamination, being further 
from the receiving platform and better inclosed. If conveyers had not 




Tig. 



-System of conveying cans and milk from the ti-ucks to tlie dump tank, located 
at a considerable distance from the entrance to the receiving room. 



been used at these plants more men would have been required. The 
necessity for a conveyer depends, of course, on the location of the 
dump tank with reference to the receiving platform. 

MILK PUMPS COMPARED WITH ELEVATORS. 

Very few plants elevated the milk to the top floor in the cans, the 
majority using pumps. Studies were made at 28 typical plants to 
determine the relative economy of the systems of (^4) dumping the 
milk in tanks on the ground floor and then pumping from this tank 
to the receiving tank above, {B) raising the milk in cans to the top 
floor by means of power conveyers, and {C) raising the cans of milk 
by means of freight elevators. If conveyers are used trouble is some- 
times experienced by a can being improperly placed on the apparatus 



CITY MILK plants: CONSTKUCTION AND ARRANGEMENT. 



15 



and the milk spilled. A comparison of the economy of the three 
systems is shown in Table 2. 

Table 2. — Comparison of men and time required to receive and dump the millc 
and tvash the cans at three different types of plants. 



Type of plant. 





Average 


Average 


Average 


Average 


Average 
hours 
of lal)or 
per 100 
cans re- 
ceived. 


Average 


Number 


cans of 


" time 


number 


hours 


time 


of 


milk 


spent 


of men 


of labor 


per 100 


plants. 


per 


per 


per 
plant. 


per 
plant. 


cans re- 




plant. 


plant. 


ceived. 






Hours. 








Hours. 


18 


1,034.7 


4.9 


4.3 


26.2 


2.5 


0.47 


6 


845 


4.9 


5.7 


30.8 


3.6 


.58 


4 


825 


8.1 


5.8 


58.4 


7.1 


.99 



Average 
cans re- 
ceived 

and 

dumped 

per 

hour. 



A (pump). .. 
B (conveyer) 
C(elevator). 



212.6 
1"2.0 
101.5 




Fig. 4. 



-Gravity conveyers bringing cans of milk from trucks to power conveyer, which 
carries them to top floor where milk is dumped. 



From the data in this table it is apparent that the system of pump- 
ing the milk from the ground floor rather than elevating it in cans 
is much more economical in the use of labor. At these plants the 
pumping system was more than twice as efficient as the elevator and 
much more efficient than the conveyer system. The conveyer sj'stem, 
however, is more economical in the use of labor than the elevator 
system and requires only about one-half as many man hours to 
handle 100 cans of milk. Of course, other factors enter into this 
problem, but these figures will illustrate the general tendency. 

In some plants it may be necessary to have the receiving room on 
the top floor because of lack of space on the ground floor, but that is 



1(3 



BULLETIN 849, U. S. DEPAETMENT OF AGRICULTURE. 



an arrangement to be avoided. Of course in plants where the number 
of cans handled is small, the element of time spent in receiving the 
milk is of less importance and conveyers or even elevators are often 
satisfactory. 



LOADING DELIVERY WAGONS. 



A study was made at several typical plants using different systems 
of loading delivery wagons, and the data obtained are shown in 
Table 3. The various systems studied were: {A) Wagons loaded in 
the interior of the building (milk trucked from storage room, no 




Fig. 5. — Dumping milk into weigh can from whicli it goes to glass-lined storage tank. 
Note gravity conveyers used to convey the empty cans from the dump tank to the can 
washer and then to carrier which conveys the clean cans down to the trucks. This 
system of receiving milk was much more economical as to time and labor required 
than the system of using freight elevators, but not so economical as the system of 
dumping the milk at the ground floor and pumping it and washing the cans 
downstairs. 

platform) ; (Z?) wagons loaded from exterior platform (milk trucked 
from storage room) ; (C) wagons loaded from exterior platform 
(milk sent on conveyers from storage room to loading platform) ; 
(D) wagons loaded direct from storage room, one small door or 
chute being used; (E) wagons loaded direct from storage room, 2 
doors or chutes being used ; (F) same as E, except that 3 doors are 
used; {(?) same as E, except that 4 or more doors are used. 

The driver is included in all cases under " Average number men 
per plant." From the column " Average hours of labor per wagon " 
in Table 3 it will be seen that the time is greatest when milk is 
loaded inside the buildin'g, and that fewest hours of labor are re- 



CITY MILK PLANTS : COISTSTRUCTION AND AERANGEMENT. 



17 



quired to handle milk loaded direct from storage room through two 
or more loading openings. In view of current labor costs this is a 
highly important point to consider in deciding on the arrangement 
of a milk plant. The cost of construction is an expense to be met 
only once, whereas the expense of labor is continuous. 

Table 3. — Comparison of time and men required to load drlircry irapons at 
plants using various systems of loading. 



System of loading. 


Num- 
ber 
of 
plants. 


Number of 

wagons loaded 

daily per 

plant. 


Aver- 
age 

num- 
ber 
men 
per 

plant. 


Aver- 
age 

hours 
of 

labor 
per 

plant. 


Aver- 
age 

hours 
of 

labor 
per 

wagon. 


Average 
time . 
per 

plant. 


Average 

time 

per 

wagon. 


Aver- 
age 

num- 
ber 

wagons 




Aver- 
age. 


Varia- 
tion. 


loaded 

per 

hour. 


.4 (inside building) 


1 

3 
1 
3 
6 
2 


22 
36.5 

52.6 

Ifi 

91 

75 

105. 5 


'2i-73" 

10-SO 

78-100 
50-130 
80-131 


4 
3.2 

6 

3 

8 

5.3 

6.5 


16 
21.11 

22.2 

7.5 

21.5 

14.5 

16.3 


0.73 

.58 

.42 
.47 
.23 
.19 
.15 


^finutcs. 
210 
314 

ISO 

150 

160 

150 

160 


Minvtes. 
10.9 
8.6 

3.4 

9.4 

1.75 

2 

1.4 


5.5 


B (exterior platform trucks). 
C (exterior platform con- 
vevers) 


7 
17.7 


D (direct from storage— 1 
door or chute) . . . 


6.4 


E (direct from storage— 2 
doors or chutes) 


34.3 


F (direct from storage— 3 
doors or chutes) 


30 


G (direct from storage — 4 or 
more doors or chutes) 


42.9 



It will be noted that there is a slightly less regular decrease in 
respect to "Average time j)er wagon," the size of the plant being a 
very important consideration in this problem. The sizes of the 
plants studied are indicated under "Average number wagons loaded 
per plant." System G would be practicable for only the larger-sized 
plants, while systems E and F would be impracticable for small 
plants. More men are usually required with systems E^ F, and G 
than with systems A, B, and D. 

It is usually desirable to load all the wagons within two or three 
hours if possible. The data in the table seem to indicate that when 
75 to 100 or more wagons are to be loaded in this time either a con- 
veyer system or a system of loading direct from the storage room 
through two or more doors or chutes is essential. While with these 
systems more men are required, the time per wagon loaded as well as 
the "Average hours of labor per wagon " loaded is considerably less 
than with the other methods, and the time element is very important 
where a considerable number of wagons are to be loaded. 

These points illustrate the inefficiency of loading wagons within 

the plant and without having a platform. The milk must be brought 

from the storage room on hand trucks and each case of milk must be 

lifted from the trucks to the wagon. If the wagons are loaded from 

158803°— 20— Bull. 849 3 



18 



BULLETIN 849, U. S. DEPAETMEISTT OF AGRICULTURE. 



a platform or from chutes which are placed so high that they come 
even with the floor of the delivery wagon, very little lifting is re- 
quired. 

The figures in Table 3 also indicate that if a platform is used the 
system of trucking the milk from the storage room is much less eco- 
nomical as to time and labor than sending the milk out on con- 
veyers. At a small plant loading only a few wagons the use of con- 
veyers may not be practicable. One or two men besides the driver 
can handle the work, while in using a conveyer sj'stem more men may 
be necessary, although the time consumed would be less. 




Fig. 6. — Loading delivery wagons at plant using system E. (The second chute was not 
in use at the time the photograph was taken.) An average of 34.3 wagons per hour 
were loaded at the three plants using this system. The average time required to load 
one wagon varied from 1.5 to 2.3 minutes. 

The table also indicates that considerable time may be saved by 
using a conveyer rather than by loading the wagons direct from the 
storage room through one door or chute ; though this means but little 
if only a few wagons are to be loaded. The hours of labor per wagon 
were not very different with the two systems, while the time per 
wagon was nearly three times as gi'eat with system D as with the 
platform-and-conveyer system. 

At plants where two or more chutes from the refrigerator room 
are used, roller conveyers generally carry the milk from the rear of 
the room to the door, and usually one class of goods is put out at each 
door. For example, quarts of milk will be put out at door No. 1, 
pints at No. 2, and cream, etc., at door No. 3. As many wagons can 



CITY MILK plants: CONSTRUGTIOlSr AND ARRANGEMENT. 



19 



be loaded at one time as there are doors. Thus the wagons are loaded 
in rapid succession and only slightly more than a minute (average) 
per wagon is required at some plants having three or more doors. 
When only one door is used more time is required per wagon. "N^T^iere 
an exterior j^latform is used, whether the milk is convej^ed from the 
storage room or trucked, usuallj^ two or more wagons may be loaded 
at the same time. 

UNLOADING DELIVERY WAGONS. 

Three systems of unloading the " returns '' from the wagons re- 
turning from the routes are shown in Table 4. 



Table 4.- 



-Time and men required to unload delivery wagons (" 7-eturns") at 
various plants using different systems. 



Type of plant. 


Number 

of 
plants. 


Average 
number 

of 
wagons 

per 
plant. 


Average 

number 

of 

men 

per 

plant. 


Average 
time 
per 

plant. 


Average 
hours 

of 

labor 

per 

plant. 


Average 
hours 

of 

labor 

per 

wagon. 


Average 
time 
per 

wagon. 


Wagons 

un- 
loaded 

per 
hour. 


A. Conveyer system (power 
or gravity) . 


8 
3 


88.4 
57.6 

21 


3.7 
2.6 


Minutes. 
177 
240 

127 


11.2 
11.5 

4.25 


0.13 
.20 

.20 


Minutes. 
2 
4.2 

6.1 


30.0 


B. Wagons unloaded on plat- 

form; then hand trucks. 

C. Wagons unloaded in in- 

terior of plant and 
hand trucks used 


14.4 
9.9 



It will be noted that for plants with a large number of wagons 
considerable time may be saved by using conveyers, as shown under 
system A, and that much time may be wasted by unloading the 
wagons within the plant. When a platform is used several wagons 
may be imloaded at one time, and when conveyers are used the 
driver simply throws liis load on to the conveyer, and in this way the 
work is done at a rapid rate. 

DIVISION OF ROOMS. 

For economy of operation and sanitation, a division of rooms is 
essential in the modern milk plant. In many small plants the greater 
part of the work is done in one room, but in the larger and more 
modem plants a special room is provided for each operation. Each 
room should be laid out and constructed for the particular purpose 
for which it is designed. 

In the receiving room the milk is inspected, sampled, and weighed. 
This room contains the weigh tank, scales, and milk-sampling out- 
fit, and should be screened and separate from the other parts of the 
plant. After the cans are. dumped they are drained, washed, steril- 
ized, . and returned. The can- washing apparatus should be located 
either in the receiving iT)om or in a room adjoining it. 



20 



BULLETIN 849, U. S. DEPARTMEISJT OF AGEICULTURE, 



Handling room. — From the receiving room the milk goes to the 
pasteurizing rooms, where it is pasteurized and cooled before going 
to the bottling room. The latter room contains the fillers and cap- 
pers and should be well lighted, ventilated, and entirely sanitary. 
This is the room that attracts the attention of visitors. The bottles 
are inspected there for the last time and plenty of light is essential. 
In some plants this room is separate, while in others the pasteurizing 
and bottling are done in the same room. Usually the pasteurizing 
vats are upon a half or mezzanine floor. It is important to have 
this milk-handling room separate from other rooms in the plant. 




Fig. 7. — Receiving room with can washer. 

Bottle -washing room. — This room should be separate so that no 
steam or foul air can j)ass into the rooms where milk is handled. 

Cleam.-'bottle storage room. — Between the bottle-washing room and 
the filling room many plants have a clean-bottle storage room where 
bottles are stored after being washed. This room must be cool and kept 
strictly clean, so that the bottles can cool and be kept free from dust 
or dirt. To obtain the best results, the air in the bottle-storage room 
is washed and artificially cooled. 

Milk-storage room. — A well-insulated cold-storage room is neces- 
sary to keep the milk cold after it is put into bottles. The construc- 
tion of cold-storage rooms is discussed on pages 12 and 24. 

Salesroom. — The salesroom at the front of the building should be 
attractive in appearance and should contain a counter, a refrigerator, 
and perhaps a few chairs and tables for customers. 



CITY MILK plants: CONSTRUCTION AND ARRANGEMENT. 



21 



Drivers^ tootyi. — A room connected with the office should be pro- 
vided in which drivers can score their books on returning from the 
routes. Bath and toilet facilities also should be provided for the 
drivers and men. 

Laboratory. — A laboratory for the bacteriological and chemical 
examination of milk is essential for all plants. Small plants need 
only a small laboratory, while large ones require a complete labora- 
tory with a full supply of chemical and bacteriological equipment. 

By-products room. — Space should be provided for handling by- 
products. Small plants require space for making only small quanti- 
ties of butter, cottage cheese, and buttermilk, which sometimes may 




Fig. 8. — Filling and capping department. The bottles, aftfer being filled and put in the 
cases, are sent on gravity conveyers to the milk-storage room. 

be done in the milk-handling room. In medium-sized or large plants, 
however, one or more separate rooms are required for the by-products 
department. 

SIZE OF ROOMS. 

Each room in the plant should be large enough to avoid crowding 
the machinery or workmen, but at the same time there should be no 
unused space, for that causes extra labor in getting from one piece of 
apparatus to another. 

There is a wide variation in the size of the various rooms in milk 
plants, as well as in floor area per 100 gallons of bottled milk handled 
daily. These variations are due in a large measure to the lack of 
standardization of milk plants and to the fact that many have been 
constructed without consideration of important factors bearing on 
the size of rooms. 



22 



BULLETIlSr 849, U. S. DEPARTMENT OF AGRICULTURE. 



Measurements from 5 modern, well-arranged plants that were built 
after careful study as to size of rooms are shown in Table 5. These 
plants were built in recent years and are giving satisfaction in regard 
to arrangement of rooms and machinery. The figures given illus- 
trate the size of rooms that give satisfaction in modern plants. 

It is important that the receiving room be of ample size. A small 
receiving room soon becomes crowded and " cluttered up " and is 
difficult to keep clean and attractive. There should be room enough 
to hold conveniently one or more truck loads of milk in cans and to 




Fig. 9. — Bottle-washing room. Note use of gravity conveyerfe. 

have plenty of room to handle the milk without crowding. It often 
happens that several loads of milk may arrive within a short space 

Table 5. — Fluor space in rarious rooms of 5 n-cU-arranycil planis of 

varunis sizes. 



Quantity 

of 
bottled 

milk 

handled 

daily. 


Receiving 
room. 


Bottle- 
washing 
room. 


Pas- 
teurizing 
room. 


Bottling 
room. 


Total 
area for 
receiving, 
washing, 
pasteuriz- 
ing, and 
bottling 
rooms. 


Milk- 
storage 
room. 


Clean- 
bottle 
storage 
room. 


Gallons. 
1,000 
1,500 
3,000 
4,000 
6,000 


Sq.ft. 
400 


Sq.ft. 

600 

700 

1,050 

1,886 

1,90S 


Sq.ft. 
500 
550 
1,300 
540 
720 


Sq.ft. 
300 
375 
1,200 
700 
720 


Sq.ft. 
1,S00 
1,625 
4,450 
3,586 
4,548 


Sq.ft. 

450 

550 

1,200 

1,426 

1,110 


Sq. ft. 
400 


900 

400 

1,200 


750 
540 
720 



of time and unless there are storage tanks it will have to remain in 
the cans in the receiving room until it can be dumped. 



CITY MILK plants: CONSTRUCTION AND ARRANGEMENT. 



23 



The size of the bottle-washing room depends somewhat on how the 
bottles are handled as they come from the delivery wagons. In 
case they have to be stacked in the wash room before being washed, 
a larger room will be required than if they pass directly from the 
delivery wagons to the washing machine and then on to the elean- 
bottle storeroom or the filling room. In case they do not have to be 
stacked, about all the space necessary is that required for the bottle- 
washing machine and ample room for the workmen to get around 
the machine. If the milk cans are washed in this room, additional 
space will be required. 




Fig. 10. — -Milk-storage room usinj; direct system of cooling with cooling coils overliead. 

Note iron plates in floor. 

The clean-bottle storage room should be large enough to accom- 
modate conveniently at least all the bottles handled in one day. If 
it is desired to store more than a day's supply of bottles at one time, 
the room necessarily would have to be larger. 

The pasteurizing room should be sufficiently large to contain the 
milk vats, clarifier, and pasteurizing equipment and still leave 
plenty of room for the men to work and to get around the machines 
for the daily cleaning. At some plants proper cleaning is often 
neglected because the men do not have space enough in w^hich to 
work. 

The bottle-filling room may be smaller than the other rooms, be- 
cause usually the bottles pass continuously through it. When there 



24 BULLETIN 849, U. S. DEPARTMENT OF AGRICULTURE. 

is no clean-bottle storage room, however, the bottle-filling room will 
have to be big enough to store the clean bottles. It should also be 
large enough to allow plenty of room for the men to get around the 
filling machines for operating and cleaning. 

The milk-storage room must be of sufficient size to hold all the milk 
that is to be handled, with space to spare for an emergency. Space 
should be allowed for a passageway between the tiers of various 
kinds of goods, such as pints and quarts of milk and jars of cream. 
Too large a room, however, is wasteful and requires additional 
refrigeration. The ceiling need not be more than 8 or 10 feet high 
after allowing for brine tank or pipes. A room 15 by 16 feet pro- 
vides a space of 240 square feet. If cases of quarts are piled 6 high 
and pints 7 high, the space would provide for about 2,000 gallons 
of bottled milk in cases. Allowing space for the men to w^ork and 
for emergencies, a room about 18 by 20 feet should be provided for 
2,000 gallons of milk in bottles. A room 12 by 15 feet would pro- 
vide space for about 1,000 gallons of bottled milk. In order to 
economize on refrigeration and insulating material the room should 
be as nearly square as possible. The proportion of milk that has to 
be held over in storage is one of the causes of the variation in size 
of storage rooms, as some plants send milk out on delivery wagons 
immediately after bottling without going to the storage room. AVhen 
large quantities of milk are stored in cans more space is required, as 
cans of milk can not.be packed so closely or so high as milk in cases 
of bottles. 

The size of the by-products room depends upon the type of busi- 
ness conducted, but ample space must be provided for the churn, 
cheese vats, and similar equipment, with plenty of room for the men 
to work. 

ARRANGEMENT OF ROOMS. 

The rooms in the plant should be arranged so as to necessitate a 
minimum expenditure for machinery and labor; the}- should be so 
laid out that the work can be carried on with the fewest possible 
steps. It is desirable that the bottle-washing room, for example, be 
handy to both the boiler room and bottle-filling room. In this way 
little steam is lost in transferring it from the boiler to the washing 
room and the washed bottles are readily transferred to the filling 
room. 

The bottle-washing room should also be so situated that the re- 
turned bottles may pass directly from the receiving platform to the 
washing machines. In some plants the bottle-washing room is di- 
rectly under or over the filling room, which may be convenient where 
there are facilities for elevating or lowering the bottles. If there is 
space enough, however, it is generally more convenient to have the 
washroom and the bottle-filling room on the first floor. 



CITY MILK plants: CONSTRUCTION AND ARRANGEMENT. 



25 



The location of the cold-storage room depends on various con- 
siderations, but if possible it should be situated so that the milk 
can go directl}^ into it from the bottling room. It should also 
be accessible to the delivery wagons, so that they can be easily and 
quickly loaded. To save refrigeration only a minimum wall surface 
of the refrigerator should be exposed to outside air or sun. Usually 
windows are unnecessary in the refrigerator. If there are windows 
they should have three or more thicknesses of glass with spaces be- 
tween, and the glass should be covered with white paint to exclude the 
direct rays of the sun. "V^Hien not needed all artificial lights should be 
extinguished, as they increase the room temperature. 



BOILeR. 
R.OOM 
iz'x iz' 



tABNS 
IZ'x O' 






VJASH B-OOAA 
16' X 20' 






COLD 

J'TORAGE 

R.OOM 

IZ' y. 12' 



k 

.1/ 



OFPICE- 
AND 

IZ' X . 16' 



n 









^. 



16' 



26' 






ijAZe- jjy/t'v-^vff 






Fig. 11. — Floor plan for a 1-story plant of about 500 gallons' daily capacity, showing 
course of milk through plant. 

The doors of the refrigerator room should fit tightly, swing out- 
ward, and be adapted to quick handling. Doors swinging inward 
reduce the storage space considerabl3\ A vestibule to the refriger- 
ator room, while taking up some extra space, prevents a considerable 
loss of refrigeration. 

ARRANGEMENT OF EQUIPMENT AND MACHINERY. 

Equipment should be arranged to permit easy cleaning. In some 
plants tanks are so placed that the man who cleans them has to 
squeeze in between the top of the tanlis and the ceiling in order to 
reach them. Much time is saved by convenient arrangement and the 
cleaner will be less liable to neglect the work. 

Machinery should be placed so as to minimize labor requirements 
and to use space most economically. Another point to be considered 
in placing the machinery is the reduction to a minimum of conveyers, 
pumps, pipes, and fittings. This applies not only to milk piping but 



26 



BULLETIN 849, U. S. DEPARTMENT OF AGRICULTURE. 



also to "water and steam piping. Large quantities of piping and 
fittings are expensive, cause extra labor, and in tlie case of milk 
pipes may be insanitary. The course of the milk through the plant 
should be as direct as possible from the receiving tank, through the 
clarifier, pasteurizer, and bottling machines to the cold-storage room. 
Mechanical conveyers should be used whenever labor and time can 
be saved; otherwise the extra expense incident to their use is not 
warranted. 






l&' " 24' 



/'/^SZSl//?/^SPJ 



24' X 24' 



BOTTLING 
R^OOM 

fz/vfw sro/?r 



OFPICF 

AND 

16' X 16 ' 



RECEIVING 



COLD- 

J^TOI^AGE- 

R.OOMJ 

FOR MILK" 

AND BUTTER. 

24' X -ZA' 



18' 



BOTTLIN^G 



R_OOA1 

A 22 ^AsK R.OOM 

I 




Fig. l: 



-Floor plans for a li-story plant of from 1,500 to 
where butter also is handled. 



,000 gallons' daily capacity. 



At 73 plants the number of milk pumps used varied from none to 
4, and the milk piping used from none to 300 feet. A wide range 
occurred in plants in the same class, as well as in plants of the same 
size. For example, at 26 plants of class 4 the length of milk piping 
varied from 20 to 210 feet, and the number of milk pumps varied 
from 2 to 4, and at 20 plants handling from 2,001 to 5,000 gallons 
daily the length of the milk piping varied from 30 to 300 feet and the 
number of milk pumps from none to 4. 

Great lengths of milk piping cause extra labor and expense and 
tend to increase the loss of milk both from milk sticking: to the sides 



CITY MILK plants: CONSTRUCTION^ AND ARRANGEMENT. 27 

of the 1311368 and from leaks at joints. If piping must be used, it 
should be of simple and sanitary construction, with frequent unions 
to permit thorough cleaning and sterilizing after each use. It is im- 
portant to have all turns in the pipes easily accessible and easily 
cleaned. Elbows and tees are to be avoided as much as possible, but 
when they are used, openings at the end will facilitate cleaning. A 
right-angle bend may be used if there is space, for in this fitting 
there are no recesses in which dirt can collect. When such joints 
are used the piping may be more easily kept clean. 

The pumps as well as the pipes should be cleaned and sterilized 
each time after using. It is less objectionable to use milk pumps 
before pasteurizing than after, for milk pumped after pasteurization 
may be recontaminated if the pump is not clean, and the added 
agitation may injure the cream line. Pumps should be of sanitary 
construction and of sufficient capacity to do the work without beino- 
overtaxed. 

EFFECT OF ARRANGEMENT OF PLANT ON LABOR REQUIREMENTS. 

The number of employees required to carry on the various opera- 
tions in the plant depends to a large degree on the laj'out and size of 
rooms, arrangement of machiner3% and size and type of building. 
Table 6 shows the number of men employed at 157 plants of various 
sizes. They include only those in the plant and in the boiler and en- 
gine rooms. In plants where ice cream is handled the time of the men 
in the power plant was prorated according to the quantities handled, 
and where there was a separate butter department the men who 
put all their time in that department were not included. The fig- 
ures given do not necessarily indicate the total number of men em- 
ployed at one plant, but one man indicates a full day for one man, 
as, for example, when the average number of employees is given as 
one, it may indicate that one man spends one-half of his time and 
two others one-fourth of their time each in the plant. 

Table 6. — Number of men employed in city milk plants of various si:;es (men 

inside the plant only). 



Capacity of plant. 



Number 
of 

plants. 



Quantity of milt 
handled daily. 



Total. Average. 



Employees in plant. 



Total. A^•c^a;.;e. Variation 



Employ- 
ees in 

plant per 

100 
gallons 

handled. 

Average. 



Gallons. 

UptolOO 

101 to 2.50 

251 to 500 

501 to 1,000 

1,001 to 1,500 

1.501 to 2,000 

2,001 to 3,000 

3,001 to 5,000 

5,001 to 10,000 

OverlO.OOO 

Total or average 



Gallons. 
2'0 
3,285 
12,435 
2fl,885 
20, 750 
19,600 
34,450 
04,650 
60, 700 
69,000 



317,975 



Gallons. 

03 

173 

401 

790 

1,297 

1,7S2 

2,650 

4,041 

7,411 

17,250 



4.3 
32.5 
86. 5 
193.0 
114. 5 
126.0 
190.0 
32S. 
294.0 
343.0 



1.1 

1.7 

2.8 

7.2 
11.5 
14.6 
20. 5 
32.7 
85. 8 



2,025 



1,711.8 



10.9 



1 to 1.3.. 

1 to3.... 
1.5 to 6.. 

2 to 13... 
2.5 to 17. 

6 to 21... 
8to27... 

7 to 36... 
9 to 49... 
49 to 100, 

1 to 100.. 



1.7 
1.0 
.7 
.7 
.0 
.6 
.6 
.5 
.4 
.5 



28 



BULLETIN 849, U. S. DEPARTMENT OF AGRICULTURE. 




.A^/Z/r 



oc/r- 



,/f/z/r' 



ocyr- 



F/LLE/^ 



COLD 




\£>U/^/^ fV^/^ 



7^A//\ 



RECeiV/NG 
/^/^A' /A( R.OOM 

^ 24' X 20' 



CLEAN BOTTLe- 
STORAG^ 
R.OOM 
zz'y- -zo' 







BOTTLe 
WAJH 
R-OOM 

J-O' X Z2' 



I 



PLATPO R.n 



Fig. 13. — First-floor plan of a two-story plant of from 2,000 to 
3,000 gallons' daily capacity. 



CITY MILK PLANTS : CONSTRUCTION AND ARRANGEMENT. 



29 



^ 
fe 



I 6' X 2.0' 



Bottling 

ROOM 

arLEAR. STOR.r 



COOC£'^ 

I ~ 






^. 



\/V/ic/////£-/i>y\ 



14 'x 20' 
ZriPfA£V^770// 






/a 

/sr 



10' X 20' 




OFFICE- 

ZZ' X -ZG' 



i ^_ 



DOWN 



TOILET 



TOILET 



^/^i^ro/f 



BY-PRODUCTS 
ROOM 

20' ^ 24-' 



DR.IVER.vJ 

scoj^e- 

R.OOM 

19' X 2^' 




LA50I^AT0R.V 

M' X 22 ' 




Fig. 13a. — Second-floor plan for a two-story plant of 
from 2,000 to 3,000 gallons' daily capacity. 

Note. — Blue prints sbowiug approved, plans for milk plants of various sizes 
and arrangements maj' be obtained free on request, by tbose contempbtting the 
erection of such plants, from the Dairy Division, U. S. Department of Agricul- 
ture, "Washington, D. C. 



30 



BULLETIN 849, U. S. DEPARTMENT OF AGRICULTURE. 



The average number of men in each phmt bears a very close rehi- 
tion to the quantity of milk handled. It will be noted, however, that 
there is a wide variation in the number of men employed at the vari- 
ous plants in each group. Some plants employ six times as many 
men as others of the same size. Although some other factors are in- 
volved, such as the relative quantities of bottled milk handled, these 
figures effectually illustrate the fact that some plants are not oper- 
ated so efficiently as others, which is due, to a great extent, to the 
fault}' layout and arrangement of rooms and machinery. Many 
plants could cut down their labor by a more economical layout of 
machinery and equipment, while others could reduce it by installing 
more labor-saving machinery. Some plants have too many floors or 
stories to be able to utilize labor efficientl}'. For example, it is often 
necessary to have a set of men with a foreman on each floor. It can 
be reaclil}^ seen that a plant with four or five floors requires more men 
and can utilize labor less efficiently than a plant handling the same 
quantity of milk with only one or two floors, although the latter plant 
may have nearly as much floor space as the larger building. The 
gravity system of milk handling (which is now generally recognized 
as the most efficient) can be used as well in a plant of 2| stories as in 
one of 4 or 5 stories. By having the pasteurizing equipment on a 
mezzanine floor, practically all the milk handling can be done in one 
room ; the gravity system of handling can be used and the number of 
men can be reduced to a minimum. 

SANITARY REQUIREMENTS. 
WATER SUPPLY. 

An abundant supply of water should be available at the plant at all 
times. Large quantities of water are required for pasteurizing and 
cooling, for boilers and refrigerating machinery, and also for wash- 
ing purposes. The quantity required for washing bottles and cans 
and cleaning up milk apparatus is considerable, and, besides, there 
are the requirements necessary for keeping the floors and walls well 
washed. Table 7 gives the quantity of water used at several plants of 
various sizes. 

Table 7. — Quauiity of iraier m^cd at milk plants of rariovs sizes. 



Capacity of plant (gallons). 



Up to 1,000... 
1,1)01 to 2,000.. 
2,001 to 3,000. . 
3,001 to .'5,000.. 
5,001 to 10,000, 
Over 10,000... 



Averasre 
quantity 

of milk 
handled 

daily. 



Oallov.i. 
."iOO 
1,.')66 
2,692 
3,500 
fi, 7SS 
15,999 



Quantity of water used daily. 



Average. 



Gallons. 
4,.v00 
14,2"-5 
11,722 
17,735 
10,135 
112,007 



Variation. 



Gallons. 

(') 
11,000 to 1S,300., 
6,710 to 17,235.. 
3,070 to 32,400.. 

(') 
102,000 to 122,01.'^ 



Quantity of water used 
daily per 100 gallons 
milk handled. 



Average. 



Gallons. 
960 
909 
436 
509 
23S 
700 



Variation. 



Gallons. 

(') 
.520 to 1,220. 
2S7 to 580. 
77 to 1,080. 

6) 
611 to 8.50. 



1 Only 1 plant in group. 



CITY MILK plants: CONSTRUCTION AND ARRANGEMENT. 31 

STEAM. 

It is important that all milk-handling equipment be sterilized im- 
mediately after washing, and plenty of live steam must be available. 
A convenient arrangement is to have a valve connected with the city 
water and with the steam system. By the use of such connection 
either hot or cold water or steam is made available. (Hot water can 
be obtained by turning on both the water and steam valves.) 

VENTILATION. 

Good ventilation is essential in a milk plant in order to get rid of 
the bad air and moisture and to insure pure air. In many plants the 
ventilation is inadequate, often being obtained by means of window^s 
and doors only. It is difficult to get good ventilation by this method. 
Even in a medium-sized plant exhaust fans should be used to take 
out the bad air and moisture. Many modern plants have an arti- 
ficial system of ventilation by which air as pure as can be obtained 
*is drawn through a filter or through a spray of water and then forced 
by fans through flues into the rooms. The openings from these flues 
or ducts into the rooms may be near the ceiling or near the floor, but 
usually they are about midway between. By heating or cooling the 
spray of Avater the temperature of the air in the rooms may be con- 
trolled to a certain extent. 

In large plants the process of filtering air consists in forcing it 
through one or more thicknesses of cheesecloth, or cloth and absorb- 
ent cotton. The air is forced into the room through the filter under 
a small j^i'essure, so that the used air has a tendency to pass out- 
ward through the openings near the ceiling provided for outgoing 
air. All air coming into the room must pass through the filter, which 
should be changed often. At some plants before the air is forced 
into the rooms it is cooled in summer by passing over brine coils and 
warmed in winter by passing over steam coils. 

For a medium or small plant there should be some system of arti- 
ficial ventilation. A flue system similar to that used in dairy barnrj 
is quite efficient and is not expensive. By simply installing outlet 
flues through which the air can pass out and allowing air to come in 
through the windows, fairly good ventilation can be obtained. 

In many plants the cold-storage room is very poorl}' ventilated. 
It is, of course, impracticable to have open windows in this room; 
consequently if an artificial system of ventilation is not used the 
ventilation is poor and the best results are not obtained from the 
cooling coils. There is also a condensation of moisture on the ceiling 
and a constant dripping, which is very uncomfortable and insanitarj^ 

In plants where artificial ventilation is impracticable considerable 
improvement can sometimes be made by using an ordinary electric 



32 



BULLETIN 840, U. S. DEPARTMENT OF AGRICULTURE. 



fan, which will keep the air in circulation and produce better results 
from the cooling coils. 

A considerable number of modern plants have an indirect 
method of cooling the cold-storage room which also serves as a ven- 
tilating system. The air is blown over bunkers or refrigerating coils 
in another room and then through flues into the cold room. The 
cold air drops as soon as it reaches the openings in this room and 
the warmer air passes out through other openings and is again 
drawn over the refrigerating coils, so that a constant circulation of 
clean, dry, cold air is maintained. 




Fig. 14. — Milk-storage room with indirect system of cooling. Note flues through which 
the cold air is fanned into the room, also system of conveying the milk into the 
room from the bottling room. 

MISCELLANEOUS KEQUIREMENTS. 

Screens should be attached to all windows and doors during the 
fly season. The screens should be outside and open outward. The 
receiving room especially should be well closed in and screened, and 
self-closing doors should be attached to the room as well as to others 
through which workmen pass continually. Electric fans will also 
aid in keeping flies away from the milk and equipment. Double 
doors at the entrance of the plant Avith fans blowing toward them 
will greatly aid in keeping the flies out. 

It is important to have a special room for tlie drivers and other 
employees. In this room a locker for each man's working clothes is 
essential, and shower baths and toilet facilities should be provided 
in an adjoining room. 



CITY MILK plants: CONSTRUCTION AND ARRANGEMENT. 33 

The milk plant frequently can operate a laundry to advantage, 
especially if the men's white working suits are washed by the plant. 
If cleaned at the milk plant's expense the men will be more likely to 
change them often. 

Aside from the general toilet facilities it is advisable to have a 
washbowl, with soap and towels handy, in the milk-handling room. 
Employees in the handling room often get their hands dirty from 
setting up machinery, handling bottles, cases, etc., and it is essential 
to have a convenient place for them to wash their hands before 
handling sterilized bottles or engaging in other operations concern- 
ing milk. 

Milk apparatus should be covered so as to expose the milk to air 
as little as possible. This caution refers especially to vats, coolers, 
and bottling machines. 

Those dealers who have a business large enough to warrant the 
maintenance of a laboratory for the careful supervision of the 
quality of milk are in a much better position to safeguard the milk 
which goes out from their plants. 

COST OF PLANT. 

The amount of money that must be invested in a milk plant depends 
primarily upon the volume of business to be carried on. Whether 
it is desirable to erect an expensive building depends on local condi- 
tions. To give some idea of the cost, Table 8 has been compiled to 
show the investment in building at 84 representative milk plants of 
different sizes. In some cases if sufficient capital is not available it 
may be desirable to rent a building for a time rather than build a 
new plant, but if a new one is built it is advisable to erect a 
permanent, sanitary building of modern construction. While the 
first cost may be high, the permanent nature of the building wiU 
make the actual overhead expense for depreciation relatively small. 

Table 8. — Investment in huildings for milk plants of various sizes; stables or 
garages for delivery equipment not included.^ 



Size of plant (gallons). 


Num- 
ber of 
plants. 


.Milk handled 
daily. 


Investment in milk 
plant. 


Investment per 100 gallons 
handled daily. 




Total. 


Average. 


Total. 


Average. 


Average. 


Variation. 


100 or less 


5 
9 
23 
14 
10 
5 
4 
8 
3 
3 


Gallons. 

430 

1,935 

9,065 

10,655 

13,040 

9,200 

10,383 

33,350 

26,000 

39,000 


Gallons. 

86 

215 

394 

761 

1,304 

1,840 

2,596 

4,169 

8,666 

13,000 


$9,000 
18,000 
86,900 
110,335 
142, 546 
116,000 
127,074 
436,763 
450,000 
534,775 


$1, 800 

2, 000 

3,778 

7,881 

14,254 

23,200 

31, 768 

54,595 

150,000 

178,258 


$2,093 
930 
958 
1,036 
1,093 
1,261 
1,224 
1,309 
1,731 
1,371 


$1,000 to $7, 143 
217 to 3,aX) 
200 to 6,000 
200 to 2,063 
333 to 2 917 


101 to 250 


251 to 500... 


501 to 1,000 


1,001 to 1,500 


1,501 to 2,000 


250 to 2,000 


2,001 to3,000 


3,001to5000 


268 to 2,000 
1,250 to 2,500 
1,233 to 1,500 


5,001 to 10,000 


Over 10,000 




Total or average 


84 153,058 1,822 j 2,031,393 


24,183 


1,327 


126 to 7,143 



* These figm-es are based on conditions a 1916-17. 



34 BULLETIN 849, V. S. DEPARTMENT OF AGRICULTURE. 

Great variations in investments in plants of the same group were 
noted. In the group handling from 251 to 500 gallons of milk daily 
this variation was from $600 to $10,000. The wide variation was 
largely due to the fact that some of the plants were old wooden build- 
ings not at all suitable for the purpose, while others were modem 
buildings of permanent construction and in some cases much more 
expensive than was necessary. 

It will be seen in Table 8 that while the average investment is di- 
rectly proportional to the quantity of milk handled, the average in- 
vestment per 100 gallons handled daily varies considerably. This 
investment is the highest for plants handling less than 100 gallons. 
Plants of that size usually have a relatively high overhead expense 
on account of the investment in buildings, except when cheap or tem- 
porary buildings are used. 

Plants handling from 101 to 250 gallons daily had an average in- 
vestment of only $200 higher than plants handling 100 gallons or 
less and also had the lowest investment per 100 gallons handled of 
all groups studied. Apparently this size of plant is economical so 
far as investment in building is concerned. As a general rule the in- 
vestment per 100 gallons handled increases with the size of the plant 
up to 10,000 gallons. This is due to a large extent to the fact that 
the general tendency is for the larger-sized dealers to have more 
elaborate plants. Although more expensive they serve as an adver- 
tising medium. The plants handling more than 10,000 gallons were 
equally well appearing, but the large quantity handled brought down 
the investment per 100 gallons. Since these figures were obtained 
there has been a great increase in the cost of materials, labor, and 

supplies. 

CONCLUSIONS. 

1. Conditions should be thoroughly investigated and found to be 
favorable before attempting to establish a milk plant. i 

2. For large plants the assistance of a competent architect in 
making plans is required. Plans for a small plant can often b^~ 
drawn without such aid. 

3. Favorable location of the milk plant is important. In general 
there are three locations that may be selected for the plant: (1) In 
a wholesale district; (2) in a down-town retail section; (3) in a 
residential section. Each of these has its advantages and disad- 
vantages. 

4. Plants may be classified, according to the way the milk is 
handled, into 6 classes. Gravity plants are to be desired, but often 
the labor required to operate plants of two or more stories is greater 
than in 1 -story plants. 

5. Large plants are usually of two or three stories. 



CITY MILK plants: CONSTRUCTIOjST AND ARRANGEMENT. 35 

6. The milk plant should be modern in every way and should be 
of good appearance from an architectural point of view. 

7. Up-to-date plants are usually constructed of bricks, concrete, 
or hollow tile, finished on the inside with smooth cement, and on the 
outside with stucco. 

8. Inside walls should have a smooth finish. Tile or enamel brick 
are desirable for the bottling and pasteurizing rooms. 

9. Concrete floors are desirable in all milk plants. Tile floors in 
the bottling rooms add to the appearance, 

10. Floors must be well drained and have proper connection with 
the sewer. 

11. Economical arrangement of the plant is important. There 
should be an outside loading and receiving platform. It is more 
economical of labor and time to dump the milk into a tank on the 
ground floor and then pump it rather than raise it by conveyers or 
elevators. To unload the milk truck on the inside of the building is 
an uneconomical arrangement. 

12. Where a large number of delivery wagons are to be loaded, 
loading through 2 or more chutes direct from the storage room will 
save time. Wagons should be loaded from an exterior platfonn, 
and conveyors are more economical in the use of labor and time than 
hand trucks. 

13. In unloading the delivery wagons a conveyer system often 
saves time and labor. 

14. For convenience, economy, and sanitation the plant should be 
divided into the following separate rooms: Keceiving room, pas- 
teurizing or handling room, bottling room, wash room, by-products 
room, milk-storage room, salesroom, offices, laboratory, etc. 

15. Each room should be of ample size to accommodate the equip- 
ment it contains, with sufficient space for the men to work and to 
clean the equipment, but there should be no' waste space. 

IG. The rooms in the plant should be so arranged as to necessitate 
the minimum expenditure for machinery and labor, and so laid out 
that the work can be accomplished with the fewest possible steps. 
There should be a minimum of milk piping and pumps, for both 
economical and sanitary reasons. 

17. Poorly arranged plants tend to increase the labor requirements. 

18. The plafit should be sanitary in every way ; plenty of water and 
steam should always be available; good ventilation and light are 
essential. 



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